This invention relates generally to vertical/short take-off and landing (hereinafter referred to as V/STOL) aircraft and particularly to surfaces to operate in slipstreams of such aircraft. More particularly, the invention relates to thrust-deflecting vanes operable doubly as tail surfaces of V/STOL aircraft. Still more specifically, the invention relates to such vanes which are operable, at the time of high-speed flight, to project as tail surfaces outward from the aircraft fuselage and, at the time of low-speed flight, to be inserted into the exhaust gas slipstream from the jet engine to deflect the same.
In general, when a V/STOL aircraft is flying at a low speed or is hovering, its ordinary control surfaces which depend on the force of flowing air lose their effectiveness, and the aircraft tends to become aerodynamically unstable. Accordingly, control of the attitude of the airframe is carried out by means of reaction jets or thrust-deflecting vanes. (Reference: Japanese Patent Application Laid-Open Publn. No. 134396/1982, Patent Publication No. 26038/1980.)
In the method of controlling the attitude of the airframe by means of reaction jets, gas or air is ejected from nozzles mounted on the airframe nose, tail, and wing tips, and the attitude of the aircraft is controlled by adjusting the thrust force, direction and ejection time of the jets thus ejected.
In the method of attitude control by means of thrust-deflecting vanes, the flow of the exhaust gas of each jet engine is deflected by one or more vanes provided in the exhaust gas flow, and the attitude of the aircraft is controlled by adjusting the moment thus obtained. (Reference: Japanese Patent Application Laid-Open Publn. No. 141753/1984, Patent Application Laid-Open Publn. No. 237147/1985.)
However, by the reaction jet method, while control of the attitude of the aircraft is possible without greatly altering the profile of the entire airframe and without causing an increase in the drag of the aircraft at the time of high-speed flight, the control power is insufficient since the bleeding capacity is inadequate. By the thrust-deflecting vane method, the control power is large, and the control force can be varied linearly, control being relatively easy. On the other hand, a large number of moving parts are required, and the mechanism becomes complicated and heavy. Furthermore, since the vanes are in the exhaust gas stream, the drag of the aircraft flying at high speed is increased.